Die casting machine



March 1954 A. w. SUNDWICK DIE CASTING MACHINE Filed June 12, 1950Patented Mar. 16, 1954 DIE CASTING MACHINE Andrew William Sundwick,Dearborn, Mich., as-

signor to General Motors Corporation, Detroit, Mich., a corporation ofDelaware I Application June 12, 1950, Serial No. 167,575

Claims.

This invention relates to improvements in die casting machines andparticularly to an insulation construction positioned within a die blockof a die casting machine for thermally insulating the die blocks fromthe nozzle.

The principal object of the invention is to provide a device forthermally insulating the heated nozzle of a die casting machine from thecooled die blocks so as to prevent rapid heat flow from the former tothe latter and thereby materially aid in creating a sharp temperaturedrop between these members. This is accomplished, in accordance with thepresent invention, by the positioning of an insulating structure withinan opening in the stationary die block. A washer of insulating materialis supported between metallic structural members, the constructionproviding only a very small area of metal-to-metal contact between thedie block and the portion of the insulating structure which contacts thehot nozzle. Such a construction permits the nozzle to remain hot and thedie blocks to remain relatively cool, thereby providing the necessaryfluidity of the metal in the gooseneck-to-die passage and also providingthe requisite lower temperature of the die blocks to insure propersolidification of the casting in the die cavity or cavities.

A further object of the invention is to provide such an insulatingmeans, located as aforementioned, which is of sturdyconstruction andwhich is easily assembled and disassembled. The present inventionfeatures an insulation construction which will not be readily displacedduring operation and which possesses sufficient structural strength toprevent its being crushed under the high compressive stresses to whichit is necessarily subjected during operation. Moreover, the insulationconstruction involved in this invention is so formed and arranged as toprevent leakage of the molten metal between the insulating means and thenozzle or between the insulating means and the adjacent stationarydieblock.

Other objects and advantages of the invention will more fully appearfrom the preferred embodiments of the invention illustrated in theaccompanying drawing, in which:

Figure l is a fragmentary longitudinal sectional view, with parts inelevation, of a die casting machine embodying the invention;

Figure 2 is an enlarged fragmentary sectional view of a stationary dieblock enclosing the heat insulating construction shown in Figure 1;

Figure 3 is a fragmentary sectional view of a modification of the dieblock and insulation construction shown in Figures 1 and 2. 7

Referring more specifically to the drawing, a melting pot H] of a typecommonly employed in commercial die casting machines is shown inFigure 1. This pot contains a supply of molten die casting metal I2 andforms a part of a furnace, indicated generally by I 4, which may befired by a gas burner or other suitable means. Suspended within themelting pot I0 is a onepiece iron casting l6 having a verticallyextending cylindrical bore which forms a pressure chamber I8. A hardenedcylindrical liner or sleeve 20 is shown as shrink-fitted within the boreand welded to the upper end of the casting I6 by welds 22. The liner andside wall of the casting have registering openings forming an intakeport or passage 24 for entry of molten metal from the pot to theinterior of the pressure chamber.

In cooperative relation with the inner walls of the liner 20 in thepressure chamber l 8 is a reciprocatory plunger or piston 26 formed ofany suitable material and shown as having its lower end grooved andprovided with a plurality of hardened steel split piston rings 28.Reoiprocation of the plunger is accomplished by securing the upper endthereof to a connecting member 30 which is attached to a suitablemechanical or fluid pressure driving means, such as an air cylinder, notshown, mounted on vertical support members 32.

A skirt or shield 34 mounted on the casting [5 over the intake port 24causes the molten metal in the melting pot to be drawn into the pressurechamber from the bottom of the pot to avoid undue agitation of themolten metal and to prevent dross from the surface from entering thepressure chamber when the level of the molten metal is allowed to fall.

The casting It has an elongated throat or gooseneck passage 36 leadingfrom the bottom of the pressure chamber is and extending upwardlytherefrom for conveying the molten metal, the lower end of the steelliner 20 having an opening 38 registering with the lower end of thegooseneck passage. The outlet end of this passage communicates with anozzle 40 through an opening 42 in a nozzle seat or spacer 44 ofhardened steel, which is fitted into the upper end of the gooseneck andserves to interconnect the entrance end of the nozzle with the gooseneckpassage. The spacer 44 is adapted to fit against the inlet end of thenozzle 4|! by the provision of a cup-shaped recess in its adjacent face.

The nozzle 40 having a longitudinal passage 4| extending axiallytherethrough is shown as extendingthrough a generally frusto-conicalopen- 3 ing 46 in a stationary platen 48. Abutting the platen andsecured thereto is a stationary die block 50, which is provided with alongitudinally extending opening 52 registering with the opening 46 inthe platen. An insulating structure, indicated generally by 54, isfitted within the stationary die block opening 52 and completes thestationary die assembly. The structure shown in Figures 1 and 2 is inthe form of a watercooled insulated sprue bushing, the constructiondetails of which will be subsequently described.

In order to insure free flowing of the metal and its retention in afluid condition until it arrives even at distant parts of the moldcavity, the nozzle 40 may be separately heated by any suitable means,such as a wide ring burner 56. Since the insulating structure insuresthat the high temperature of the nozzle 40 shall not unduly heat thestationary die block 52 itself, the absorption of heat from the castingby the die block is not interfered with.

On a movable platen or die holder 58 secured to a slidable carriage, notshown, is mounted a suitable movable die block 60 adapted to mate withthe stationary die block 50 to define the die cavity or cavities, alsonot shown. A die core or sprue spreader 64 is fitted in a recess in theworking face of the stationary die and shown as secured thereto by asuitable set screw 66.

The tapered, rounded end of the sprue spreader,

which projects into the sprue 68 within the stationary die assembly toform an internal molding surface, may also be water-cooled to providefor more rapid cooling of the casting in the sprue.

The supporting and actuating mechanisms for the movable die are notshown in complete detail herein since they form no part of theinvention, it being sufficient to state that the various portions of thedie blocks and their actuating mechanism are supported in position topermit reciprocation of the die holder 58 supporting the movable dieblock and of an ejector supporting plate I on which are mounted the endsof ejector pins 12. These movable members are adapted to be'reciprocably driven by any suitable mechanical or fluid pressure means,not shown.

After the die blocks are closed, molten metal from the pot I0, enteringthe pressure chamber through the passage 24, is forced by thereciprocatory plunger 26 through the gooseneck 36, through the passages42 and M in the spacer and nozzle, respectively, through the sprue 68and into the passages or runners B2 to the die cavities. Uponsolidification of the die casting metal, the die blocks are separatedand the ejector ins are advanced to force the castings out of themovable die 58 and off the core 64, after which the gate is usuallyremoved manually. The die blocks are then closed and the cycle repeated.In the form shown in Figures 1 and 2, the insulating structure 54,hereinbefore mentioned, is in the form of an assembly which includes asleeve or insert 14 fitted into the opening 52 in the stationary dieblock 50. This sleeve is provided with an outwardly extending flange 16which abuts a shoulder I8 on the die block to prevent axial movement ofthe sleeve relative to the die block. A preferably cylindrical extension80 of the sleeve, shown with a reduced diameter, projects axially towardthe nozzle 40. Fitted around the extension 00 of the sleeve and havingan edge abutting the larger face of the flange I6 is shown an annularcollar 82, which may be secured to the sleeve by welding, as indicatedby 84. This collar has its face nearest the nozzle provided with anannular recess 86 having a base in the same plane as the adjacent endface of the sleeve I4 for seating a preferably annular insulating washer88 of mica or other suitable insulating material. This insulatingwasher, therefore, abuts not only the adjacent end face of the collarbut also a portion of the end surface of the sleeve extension 80.

As shown in Figures 1 and 2, water or other fluid cooling of the spruebushing may be provided for by forming a portion of the inner peripheralsurface of the collar 82 with a groove to define, together withextension 80, an annular passage 90. Cooling water may be forced throughthis passage to further contribute to the rapid temperature drop in themetal flowing from the heated nozzle to the die cavities.

While the sleeve 14 and the collar 82 are shown as formed in two parts,it will be appreciated that some of the functions of the invention couldbe performed if these parts were made integral, the coolant passage, ifdesired, being formed by a separate machining operation.

The insulating washer 88 is clamped in position by a metallic retainerplate 92, preferably cylindrical in shape and provided with a generallycentral opening, which plate is shown as secured to the collar 82 bywelds 94. The inner face of this plate has an axially projectingshoulder 95 adjacent the sprue positioned within a recess 88 in the endof the sleeve I4 and abutting the base surface thereof. The peripheralsurface of the shoulder 96 positioned against the side walls of therecess 98 in the sleeve further aids in maintaining radial alignment ofthe plate 92 relative to the sleeve as well as positioning theinsulating washer 88. Moreover, the extension '14 serves to seal theinsulating washer from the sprue, thereby preventing seepage of themolten die casting metal I00 in the sprue into the insulating washerunder high die casting pressures, which seepage would cause rapiddeterioration of the washer. The intake face of the retainer plate 10 isprovided with a concave recess I02 into which is seated the roundedoutlet tip of the nozzle 36.

Fastening means, such as a screw I04, provided with a washer I 06 whichoverlaps a recessed portion I 08 of the outer end face of the retainerplate 92, may be employed to prevent axial movement of the insulatedsprue bushing toward the nozzle.

Referring to the insulating construction shown in Figure 3, thestationary die block I50 has its intake face provided with a recess I52,preferably of a generally cylindrical shape. Positioned within thisrecess and seated against the base thereof is a relatively thin washerI88 of mica or other suitable insulation material. This insulatingwasher is provided with a central aperture I90 which registers with alongitudinally extending opening I92 in the die block I50.

Also located with the recess I52 is a metallic retainer plate or bushingI 94 having one face abutting the insulating washer I88 and its oppositeface preferably provided with a concave recess I93 for seating therounded tip of the nozzle 40. The plate I94 is preferably annular andprovided with a central aperture I98 registering with the aperture I90in the insulating washer I88 and with the opening 4| in the nozzle. Thisplate may be advantageously constructed of hardened steel with its outerperipheral edges tapered to provide practically only line contactbetween these edges and the side walls of the die block recess I52, asindicated at 198.

A securing device, such as a screw 200, may e used to retain theretainer plate in position, this construction permitting the readyremoval of the plate for replacement of the insulating washer 88.

t will be noted that, inasmuch as the insulating Washer extendscompletely to the sprue passage ISQ-Jlit-Illt, the construction shown inFigure 3 results in minimum metal-to-metal contact between the plateI94, which is in heat conductive contact with the hot nozzle 40, and thestationary die block I50. Furthermore, an annular groove 292 may beprovided in the inner face of the metal plate I94 to also reduce thearea of contact between the plate and the insulating washer. A smallannular contact surface 29 on the same face of the plate near its outeredges is desirable to insure flush seating of the plate and to enable itto withstand the high compressive stresses to which it is subjectedduring operation.

It can be seen, therefore, that this structure effectively thermallyinsulates the nozzle from the die, the axial passage of heat from theformer to the latter being prevented by the insulating washer I88. Heatis also prevented from being transmitted radially from the retainerplate I94 to the die block because of the small area of contact betweenthese members, the generally annular spaces 296 functioning asinsulating spaces. The small additional contact area between metallicsurfaces resulting from the presence of the screw 200 does notmaterially affect the efiiciency of this insulating structure.

It will be noted that the danger of the molten metal, while underpressure, seeping into the in" sulating washer I98 is substantiallyreduced in this modification shown in Figure 3 by having thea plate assextend radially into the sprue toa greater extent than does theinsulating washer, as indicated at 298. The offset thereby providedprevents the washer from being subjected to the dynamic pressure of theflowing molten metal.

While the described embodiments of the present invention constitutepreferred forms, it is to be understood that other modifications andvariations in details of structure and arrangement may be made withoutdeparting from the scope of the invention as defined in the appendedclaims.

I claim:

1. In a die casting machine having a movable die block and a cooperatingstationary die block with an opening extending therethrough forreceiving molten die casting metal from a nozzle, an insulatingstructure fixed within said opening for thermally insulating the dieblocks from the nozzle, said insulating structure comprising a metallicplate member and a washer of insulating material having one faceabutting supporting surfaces of the stationary die assembly and itsopposite face abutting the plate member and secured thereby, said platemember having its face remote from the washer recessed for seating thetip of the nozzle, said washer and plate member provided withregistering openings for the conveyance of molten metal therethrough.

2. In a die casting machine having a die block with an opening extendingtherethrough for receiving molten metal from an end of a nozzle, aninsulating assembly fitted within said opening and comprising a metallicsleeve, a metallic collar member surrounding said sleeve and definingwith it a passage for the circulation therethrough of a fluid coolant, ametallic retainer plate positioned between the nozzle and the collarmember and sleeve and having one face provided with a recess for seatingthe end of the nozzle, and a washer of insulating material supportedbetween the other face of the retainer plate and the adjacent end facesof the collar member and sleeve for thermally insulating said collarmember and said sleeve from said plate, said sleeve, retainer plate andwasher being provided with generally aligned openings for receivingmolten metal from said nozzle.

3. In a die casting machine having a movable die block and a cooperatingstationary die block with an opening extending therethrough forreceiving molten metal from a nozzle, an insulating structure fixedwithin said opening for thermally insulating the die blocks from thenozzle, said insulating structure comprising a washer of insulatingmaterial having one face abutting a portion of the walls of thestationary die block opening and a metallic retainer plate having itsperipheral edges tapered outwardly and contacting the walls of thestationary die block opening, said plate having one face abutting saidwasher for the securing thereof and its opposite face provided with arecess for seating the tip of the nozzle, said washer and plate beingprovided with registering openings for the conveyance of molten metaltherethrough.

4. In a die casting machine having a die block with an opening extendingtherethrough for receiving molten metal from a nozzle, a metallic memberpositioned within the opening having one face in direct heat conductingrelation with the tip of said nozzle and having a passage for receivingmolten metal from said nozzle, and a member of insulating materialhaving a corresponding passage abutting the opposite face of saidmetallic member for thermally insulating the die block from the metallicmember.

5. In a die casting machine having a die blocl: with an openingextending therethrough for receiving molten metal from a nozzle, ametallic sleeve positioned within said opening, a layer of insulatingmaterial for thermally insulating the die block from the nozzle alsolocated within said opening and abutting one end of said metallicsleeve, and a metallic plate having one face positioned against thelayer of insulating material and its opposite face in direct heatconductive relation with the tip of said nozzle, said metallic sleeve,plate and layer of insulating material being provided with registeringopenings for conveying molten metal from the nozzle.

ANDREW WILLIAM SUNDWICK.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,458,482 Grey June 12, 1923 1,673,838 Lester June 19, 19281,948,992 Morin Feb. 2'7, 1934 1,952,201 Flammang et al. Mar. 27, 19342,000,488 Korsmo May '7, 1935 2,058,378 Freund Oct. 20, 1936 2,242,350Eldred May 20, 1941 2,413,401 Youngblood et al. Dec. 31, 1946 FOREIGNPATENTS Number Country Date 598,045 Great Britain Feb. 9, 1948

